[Doc] Add Cambricon MLU support

[a120092009]

We have open-sourced vllm-mlu and contributed documentation support to the vLLM community.​

Purpose

Test Plan

Test Result

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[github-actions]

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[gemini-code-assist]

Code Review

This pull request adds documentation for Cambricon MLU support by including it in the list of hardware plugins. The change is straightforward and correctly formatted, consistent with the existing entries in the installation guide. I have reviewed the changes and found no issues.